DE102019002732A1 - Method for the direct transfer of electronic coin data sets between terminals and payment systems - Google Patents

Abstract

The invention relates to a method for the direct transmission of electronic coin data sets between terminals, wherein a first terminal has at least one electronic coin data set, with the steps of: transmitting the electronic coin data set from the first terminal to a second terminal, the at least one electronic coin data set at least one monetary amount and has an amount of obfuscation; Receiving the electronic coin data record from the first terminal as a transmitted electronic coin data record in the second terminal; and switching over the transmitted electronic coin data record, splitting the transmitted electronic coin data record and / or connecting the transmitted electronic coin data record. The method further comprises the steps of masking the further electronic coin data record in the second terminal by applying a homomorphic one-way function to the further electronic coin data record to obtain a masked electronic coin data record; and registering the masked electronic coin record with a remote monitoring entity. The invention also relates to a currency system and a payment system with a decentrally controlled database in which masked electronic coin data records are stored; and a direct transaction layer with at least two terminals in which the method can be carried out.

Description

TECHNICAL FIELD OF THE INVENTION

The invention relates to a method for the direct transmission of electronic coin data sets between terminals. The invention also relates to a payment system between at least two terminals and a monitoring entity.

TECHNICAL BACKGROUND OF THE INVENTION

Security of payment transactions and the associated payment transaction data means protection of the confidentiality of the data exchanged; as well as protecting the integrity of the data exchanged; as well as protection of the availability of the exchanged data.

Conventional blockchain-based payment transactions such as Bitcoin represent a high level of protection of integrity. When electronic coin data records, also known as “coins”, change hands in a blockchain technology, a lot of information is published. Such payment transactions and in particular the data exchanged are therefore not completely confidential. In addition, the payment transactions are very computationally intensive and therefore energy-consuming.

Therefore, instead of the confidential data, only the hash values of the confidential data are conventionally stored in a blockchain ledger. The corresponding plain text data must then be managed outside the blockchain. For electronic coin data sets, such concepts are so far not applicable because they have basic control functions, in particular ( 1 ) the recognition of multiple expenditure procedures, also called double-spending, and (2) the recognition of uncovered payments. In case (1) someone tries to output the same coin data record several times and in the second case someone tries to output a coin data record even though he has no credit (or no longer).

From the DE 10 2009 038 645 A1 and the DE 10 2009 034 436 A1 systems for the transfer of monetary amounts in the form of electronic data records, in which payment with duplicates of the data record is prevented and a high degree of manipulation security is given, are known, complex structures and complex encryption and signing processes are required for exchange. They turned out to be of little practical use.

In the WO 2016/200885 A1 describes a method for encrypting an amount made in a blockchain ledger, whereby the verifiability of the transaction is retained. A concealment amount is added to an input value. Then an output value is generated and encrypted. Both the input value and the output value lie within a value range, with a sum of any two values within the range not exceeding a threshold value. The sum of the encrypted input value and the encrypted output value can be zero. Range tests, so-called range proofs, are assigned to each of the input values and the output value. These range checks prove that the input value and output value fall within the range of values. Each public key can be signed with a ring signature based on a public key of a recipient in the transaction. This process requires blockchain technology, which must be called after receiving a coin data set in order to validate the coin data set.

It is the object of the present invention to create a method and a system in which a payment transaction is designed to be secure but nevertheless simple. In particular, direct payment between end devices such as tokens, smartphones and machines should be created that is anonymous. The coin data records should be able to be used immediately after receipt. Several coin data sets should be able to be combined with one another and / or divided as desired by the user in order to enable flexible exchange. The exchanged coin data sets should on the one hand be confidential to other system participants, but on the other hand allow each system participant to carry out basic accounting checks, in particular the recognition of "multiple spending attempts" and the recognition of attempts to pay with non-existent amounts.

SUMMARY OF THE INVENTION

The tasks set are achieved with the features of the independent patent claims. Further advantageous configurations are described in the dependent claims.

• Übertragen des elektronischen Münzdatensatzes vom ersten Endgerät an ein zweites Endgerät, wobei der zumindest eine elektronische Münzdatensatz mindestens einen monetären Betrag und einen Verschleierungsbetrag aufweist;

The object is achieved in particular by a method for the direct transmission of electronic coin data sets between terminals, a first terminal having at least one electronic coin data set, with the steps:

• Transmitting the electronic coin data record from the first terminal to a second terminal, the at least one electronic coin data record having at least one monetary amount and a concealment amount;

• - Umschalten des übertragenen elektronischen Münzdatensatzes zu einem weiteren elektronischen Münzdatensatz, nämlich umzuschaltenden elektronischen Münzdatensatz; und/ oder
• - Aufteilen des übertragenen elektronischen Münzdatensatzes zu einem weiteren (zweiten) elektronischen Münzdatensatz; und/ oder
• - Verbinden des übertragenen elektronischen Münzdatensatzes mit einem weiteren elektronischen Münzdatensatz zu einem weiteren elektronischen Münzdatensatz, nämlich verbundenen elektronischen Münzdatensatz.

Receiving the electronic coin data record from the first terminal as a transmitted electronic coin data record in the second terminal; and

• - Switching the transmitted electronic coin data set to a further electronic coin data set, namely electronic coin data set to be switched; and or
• Splitting the transmitted electronic coin data set into a further (second) electronic coin data set; and or
• - Linking the transmitted electronic coin data set with a further electronic coin data set to form a further electronic coin data set, namely connected electronic coin data set.

• - Maskieren des weiteren elektronischen Münzdatensatzes im zweiten Endgerät durch Anwenden einer homomorphen Einwegfunktion auf den weiteren elektronischen Münzdatensatz zum Erhalten eines maskierten elektronischen Münzdatensatzes; und
• - Registrieren des maskierten elektronischen Münzdatensatzes in einer entfernten Überwachungsinstanz.

The method also includes the following steps:

• Masking the further electronic coin data set in the second terminal by applying a homomorphic one-way function to the further electronic coin data set to obtain a masked electronic coin data set; and
• - Registering the masked electronic coin data record in a remote monitoring entity.

The steps described here do not have to be carried out in the order described. However, the order described here is a preferred embodiment.

The step of registration is preferably carried out when the devices are connected to the monitoring entity. As an alternative, the steps described can also be carried out without the step of registering in the monitoring instance being carried out.

When switching over the transmitted coin data record, in one embodiment the monetary amount of the transmitted electronic coin data record from the first terminal corresponds to the monetary amount of the further electronic coin data record. When dividing the transmitted electronic coin data record, in one embodiment the monetary amount of the transmitted electronic coin data record corresponds to the monetary total amount of the further electronic coin partial data records created from the transmitted electronic coin data record. When connecting, in one embodiment, the total monetary amount from the transmitted electronic coin data record with the second electronic coin data record corresponds to the monetary amount of the connected electronic coin data record.

An electronic coin dataset is in particular an electronic dataset that represents a monetary amount and is colloquially referred to as "digital coin" or "electronic coin". In the process, this monetary amount changes from a first terminal to another terminal. In the following, a monetary amount is understood to be a digital amount, e.g. can be credited to an account of a financial institution, or can be exchanged for another means of payment. An electronic coin data record therefore represents cash in electronic form.

The terminal device can have a large number of electronic coin data records, for example the large number of coin data records can be stored in a data memory of the terminal device. The data memory then represents an electronic wallet, for example.

The terminal can, for example, be a passive device, such as. B. a token, a mobile device such as a smartphone, a tablet computer, a computer, a server or a machine.

An electronic coin dataset for transferring monetary amounts differs significantly from an electronic dataset for data exchange or data transfer, since, for example, a classic data transaction takes place on the basis of a question-answer principle or on intercommunication between the data transfer partners. An electronic coin data record, on the other hand, is unique, unambiguous and is in the context of a security concept that can include signatures or encryptions, for example. In principle, an electronic coin data record contains all data that are required for a receiving entity with regard to verification, authentication and forwarding to other entities. Intercommunication between the end devices during the exchange is therefore basically not necessary with this type of data record.

According to the invention, an electronic coin dataset used for transmission between two terminals has a monetary amount, that is to say a date which represents a monetary value of the electronic coin dataset, and a concealment amount, for example a random number. In addition, the electronic coin data record can have further metadata, for example which currency the monetary amount represents. An electronic coin data set is uniquely represented by these at least two data (monetary amount and concealment amount). Anyone who has access to these two pieces of data from a valid coin data record can use this electronic coin data record for payment. Knowing these two values (monetary amount and obfuscation amount) is synonymous with owning digital money. This electronic coin data record is transmitted directly between two terminals, namely at least between the first and second terminal. In one embodiment of the invention, an electronic coin dataset consists of these two data, so that only the transfer of the monetary amount and the concealment amount is necessary for exchanging digital money.

A corresponding masked electronic coin data record is assigned to each electronic coin data record. The knowledge of a masked electronic coin data record does not entitle one to dispense the digital money which is represented by the electronic coin data record. This represents an essential difference between masked electronic coin data records and (unmasked) electronic coin data records and is the core of the present invention. The masked electronic coin data record is unique and can be clearly assigned to an electronic coin data record, i.e. a 1-to-1 relationship. The electronic coin data set is preferably masked by a computing unit of the terminal within the terminal which also has the at least one electronic coin data set. Alternatively, the masking can be done by a computing unit of the terminal that receives the electronic coin data record.

This masked electronic coin data set is obtained by applying a homomorphic one-way function, in particular a homomorphic cryptographic function. This function is a one-way function, i.e. a mathematical function that is “easily” computable in terms of complexity theory, but “difficult” or practically impossible to reverse. Here, a one-way function is also referred to as a function for which no reversal that can be practically carried out in a reasonable time and with reasonable effort is known. The calculation of a masked electronic coin data record from an electronic coin data record is thus comparable to the generation of a public key in an encryption process using a residual class group. Preferably, a one-way function is used which operates on a group in which the discrete logarithm problem is difficult to solve, such as e.g. B. a cryptographic method analogous to an elliptical curve encryption, ECC for short, from a private key of a corresponding cryptography method. The reverse function, i.e. the generation of an electronic coin data record from a masked electronic coin data record, is very time-consuming - equivalent to generating the private key from a public key in an encryption process over a residual class group. When sums and differences or other mathematical operations are mentioned in the present document, the respective operations on the corresponding mathematical group are to be understood in the mathematical sense, for example the group of points on an elliptical curve.

The one-way function is homomorphic, i.e. a cryptographic method that has homomorphic properties. Thus, mathematical operations can be carried out with the masked electronic coin dataset, which can also be carried out in parallel on the (unmasked) electronic coin dataset and can therefore be reproduced. With the help of the homomorphic one-way function, calculations with masked electronic coin data records can be carried out in the monitoring instance can be reproduced without the corresponding (unmasked) electronic coin data records being known there. Therefore, certain calculations with electronic coin data records, for example for processing the (unmasked) electronic coin data record (e.g. splitting or combining), can also be verified in parallel with the associated masked electronic coin data records, e.g. for validation checks or to check the legality of the respective electronic coin data record . The homomorphism properties apply at least to addition and subtraction operations, so that splitting or combining (= connecting) electronic coin data sets can also be recorded in the monitoring instance by means of the correspondingly masked electronic coin data sets and can be traced by requesting end devices and / or by the monitoring instance, without knowing the monetary amount and the performing terminal.

The homomorphism property therefore makes it possible to enter valid and invalid electronic coin data records on the basis of their masked electronic coin data records in a monitoring instance without knowledge of the electronic coin data records, even if these electronic coin data records are processed (divided, connected, switched). This ensures that no additional monetary amount has been created or that an identity of the terminal is recorded in the monitoring instance. Masking thus enables a high level of security without giving any insight into the monetary amount or the end device. This results in a two-tier payment system. On the one hand there is the processing layer in which masked electronic data records are checked and on the other hand there is the direct transaction layer in which at least two terminals transmit electronic coin data records.

While the electronic coin data records are used for direct payment between two terminals, the masked coin data records are registered in the monitoring instance.

• - Generieren eines umzuschaltenden elektronischen Münzdatensatzes im zweiten Endgerät aus dem übertragenen Münzdatensatz, wobei
• - ein Verschleierungsbetrag für den umzuschaltenden elektronischen Münzdatensatz unter Verwendung eines übertragenen Verschleierungsbetrags des übertragenen elektronischen Münzdatensatzes im zweiten Endgerät erzeugt wird; und
• - der übertragene monetäre Betrag des übertragenen elektronischen Münzdatensatzes als monetärer Betrag für den umzuschaltenden elektronischen Münzdatensatz verwendet wird.

The step of switching over the transmitted electronic coin data record comprises the following sub-steps:

• - Generating an electronic coin data set to be switched in the second terminal from the transmitted coin data set, wherein
• a concealment amount for the electronic coin data record to be switched is generated in the second terminal using a transmitted concealment amount of the transmitted electronic coin data record; and
• the transmitted monetary amount of the transmitted electronic coin data set is used as the monetary amount for the electronic coin data set to be switched.

When the electronic coin data record is transferred from the first terminal to the second terminal, two terminals are thus aware of the electronic coin data record. In order to prevent the sending first terminal device from also using the electronic coin data record for another (third) terminal device for payment, the transmitted electronic coin data record is switched from the first terminal device to the second terminal device. Switching can preferably take place automatically when receiving an electronic coin data record. In addition, it can also be done on request, for example a command from the first and / or second terminal.

In a preferred embodiment, the generation includes generating a In a preferred embodiment, the generation includes generating a concealment amount for the electronic coin data set to be switched, preferably using the concealment amount of the transmitted electronic coin data set in conjunction with a new concealment amount, for example a random number. The concealment amount of the electronic coin data record to be switched is preferably obtained as the sum of the concealment amount of the transmitted electronic coin data record and the random number that serves as the new, that is, additional concealment amount. Furthermore, the monetary amount of the transmitted electronic coin dataset is preferably used as the monetary amount for the electronic coin dataset to be switched. This means that no further money is generated, the monetary amounts of both coin data sets are identical.

The registration after the switching step has the result that the electronic coin data set sent by the first terminal becomes invalid and is recognized as correspondingly invalid on a second dispensing attempt by the first terminal. The (further) coin data set generated by the second terminal device becomes valid after the tests have been successfully completed.

When switching, also called “switch”, the electronic coin data record received from the first terminal results in a new electronic coin data record, preferably with the same monetary amount, the so-called electronic coin data record to be switched. The new electronic coin data record is generated by the second terminal, preferably by using the monetary amount of the received electronic coin data record as the monetary amount of the electronic coin data record to be switched. A new concealment amount, for example a random number, is generated. The new concealment amount is added, for example, to the concealment amount of the received electronic coin data record so that the sum of both concealment amounts (new and received) serves as the concealment amount of the electronic coin data record to be switched. After switching, the electronic coin data set received and the electronic coin part data set to be switched are preferably masked in the terminal by applying the homomorphic one-way function to the respective electronic coin data set received and the electronic coin part data set to be switched in order to obtain a masked received electronic coin data set and a masked electronic coin part data set to be switched accordingly. Furthermore, additional information which is required for registering the switching of the masked electronic coin data record in the remote monitoring entity is preferably calculated in the terminal. The additional information preferably contains an area proof of the masked electronic coin data record to be switched over and a region proof of the masked electronic coin data record obtained. The area evidence is evidence that the monetary value of the electronic coin data record is not negative, the electronic coin data record is validly created and / or the monetary value and the concealment amount of the electronic coin data record are known to the creator of the area evidence. In particular, the area verification serves to provide this verification (s) without revealing the monetary value and / or the concealment amount of the masked electronic coin data record. These proofs of range are also called “zero knowledge range proofs”. Ring signatures are preferably used as area evidence. The switching of the masked electronic coin data record is then registered in the remote monitoring entity.

This switching is necessary in order to invalidate (invalidate) the electronic coin data set received from the first terminal in order to avoid double spending. Because, as long as the electronic coin data record is not switched over, the first terminal can pass this received electronic coin data record on to a third device - since the first terminal is aware of the electronic coin data record and is therefore still in its possession. Switching is secured, for example, by adding a new concealment amount to the concealment amount of the electronic coin data record obtained, whereby a concealment amount is obtained that only the second terminal device knows. Newly created obfuscation amounts must have a high entropy, since they are used as a dazzle factor for the corresponding masked electronic coin part data records. A random number generator on the terminal is preferably used for this purpose. This protection can be tracked in the monitoring instance.

In the dividing step, the electronic coin data record of the second terminal is divided into the first electronic coin partial data record and the second electronic coin partial data record. The splitting is preferably done in that, on the one hand, a monetary partial amount and a partial concealment amount is specified for the first electronic coin data record (each between 0 and the received monetary amount or concealment amount) and, on the other hand, the monetary amount of the second electronic coin partial data record as the difference from the obtained monetary amount and the monetary partial amount of the first electronic coin part data set, and the concealment amount of the second electronic coin part data set is calculated as the difference between the received concealment amount and the partial concealment amount of the first electronic coin part data set. After the division, the electronic coin data set to be divided, the first electronic coin part data set and the second electronic coin part data set are masked in the second terminal by applying the homomorphic one-way function in each case in order to obtain a masked electronic coin data set to be divided, a masked first electronic coin part data set and a masked second electronic coin part data set . Furthermore, additional information that is required for registering the division of the masked electronic coin data record in the remote monitoring entity is calculated in the terminal. The additional information preferably includes an area evidence of the masked electronic coin data record to be split, an area evidence of the masked first electronic coin data record and an area evidence of the masked second electronic coin data record. The area evidence is evidence that the monetary value of the electronic coin data record is not negative, the electronic coin data record is validly created and / or the monetary value and the concealment amount of the electronic coin data record is passed on to the creator of the Area evidence are known. In particular, the area verification is used to provide this verification (s) without revealing the monetary value and / or the concealment amount of the masked electronic coin data record. These proofs of range are also called “zero knowledge range proofs”. Ring signatures are preferably used as area evidence. Subsequently, the division of the masked electronic coin data set is registered in the remote monitoring entity. In this way, monetary amounts to be transferred can be adapted to the corresponding needs. A terminal owner is not forced to always pass on the entire monetary amount to another terminal.

The splitting and subsequent registration has the advantage that an owner of the at least one electronic coin data record is not forced to always transfer the entire monetary amount at once, but instead to transfer corresponding sub-amounts. The monetary value can be divided without restrictions as long as all electronic coin data sub-records have a positive monetary amount that is less than the monetary amount of the electronic coin data record from which the division is made and the sum of the electronic coin sub-data records is equal to the electronic coin sub-data record to be divided. Alternatively or additionally, fixed denominations can be used. Alternatively, the concealment amount can be generated outside of the terminal and obtained via a (secure) communication channel. A random number generator on the terminal is preferably used for this purpose. In order to keep track of all checks, the checking instance can, for example, note the sub-steps of the monitoring instance in appropriate places, with markings, English flags, also being set for this purpose in order to document intermediate stages. After successfully completing the checks that are relevant for the split command, that is, if the markings are complete, the (masked) first electronic coin part data record and (masked) second electronic coin part data record are preferably marked as valid. The (masked) electronic coin data set to be split automatically becomes invalid. The monitoring instance preferably notifies the "commanding" terminal of the result of executing the split command, i.e. which of the masked electronic coin data sets involved are valid after the split command has been executed.

In the step of connecting electronic coin data sets, a further electronic coin data set (connected electronic coin data set) is determined from a first and a second electronic coin data set. The concealment amount for the electronic coin data set to be linked is calculated by forming the sum from the respective concealment amounts of the first and second electronic coin data sets. Furthermore, the monetary amount for the connected electronic coin dataset is preferably calculated by forming the sum from the respective monetary amounts of the first and the second electronic coin dataset.

After connecting, the first electronic coin data set, the second electronic coin data set and the electronic coin data set to be connected are saved in the (first and / or second) terminal by applying the homomorphic one-way function to the first electronic coin data set, the second electronic coin data set and the one to be connected electronic coin data record masked in order to obtain a masked first electronic coin data record, a masked second electronic coin data record, and a masked electronic coin data record to be connected accordingly. Furthermore, additional information that is required for registering the connection of the masked electronic coin data records in the remote monitoring entity is calculated in the terminal. The additional information preferably includes an area evidence of the masked first electronic coin data record and an area evidence of the masked second electronic coin data record. The area evidence is evidence that the monetary value of the electronic coin data record is not negative, the electronic coin data record is validly created and / or the monetary value and the concealment amount of the electronic coin data record are known to the creator of the area evidence. In particular, the area verification is used to provide this verification (s) without revealing the monetary value and / or the concealment amount of the masked electronic coin data record. These proofs of range are also called “zero knowledge range proofs”. Ring signatures are preferably used as area evidence. The connection of the two masked electronic coin data records is then registered in the remote monitoring entity.

With the command or step of connecting two electronic coin data sets can be combined. The monetary amounts as well as the obfuscation amounts are added up. As with dividing, the two original coin data records can also be validated when combining.

A main distinguishing feature of this inventive concept compared to known solutions is that the monitoring instance only (that is, exclusively) maintains knowledge of the masked electronic coin data records and a list of processing or changes to the masked electronic coin data record. The actual payment transactions are not registered in the monitoring instance and take place in a direct transaction layer directly between terminals.

According to the invention, a two-layer payment system consisting of a direct payment transaction layer for the direct exchange of (unmasked) electronic coin data records and a monitoring layer, which can also be referred to as a “veiled electronic data record ledger”, is provided. In the monitoring instance of the verification layer, no payment transactions are recorded, only masked electronic coin data records and their processing for the purpose of verifying the validity of (unmasked) electronic coin data records. This guarantees the anonymity of the participants in the payment system. The monitoring instance provides information about valid and invalid electronic coin data sets, for example to avoid multiple issuance of the same electronic coin data set or to verify the authenticity of the electronic coin data set as validly issued electronic money.

The first and / or second terminal can thus transmit electronic coin data records to another terminal in the direct payment transaction layer without a connection to the checking entity, in particular when the terminal is offline.

In the present case, the first and / or second terminal can have a security element in which the electronic coin data records are securely stored. A security element is preferably a special computer program product, in particular in the form of a secured runtime environment within an operating system of a terminal, English Trusted Execution Environments, TEE, stored on a data memory, for example a mobile terminal, a machine, preferably an ATM. Alternatively, the security element is designed, for example, as special hardware, in particular in the form of a secured hardware platform module, English Trusted Platform Module, TPM or as an embedded security module, eUICC, eSIM. The security element provides a trustworthy environment.

The communication between two terminals can be wireless or wired, or e.g. also take place optically, preferably via QR code or barcode, and can be designed as a secure channel. The optical path can include, for example, the steps of generating an optical coding, in particular a 2D coding, preferably a QR code, and reading in the optical coding. The exchange of the electronic coin data record is thus secured, for example, by cryptographic keys, for example a session key negotiated for an electronic coin data record exchange or a symmetrical or asymmetrical key pair.

By communicating between end devices, for example via their security elements, the exchanged electronic coin data sets are protected against theft or manipulation. The security element level thus complements the security of established blockchain technology.

In addition, it is advantageous that the electronic coin data records can be transmitted in any format. This implies that it communicates on any channel, i.e. that it can be transmitted. They do not need to be saved in a specific format or in a specific program.

In particular, a mobile telecommunication terminal, for example a smartphone, is regarded as a terminal. As an alternative or in addition, the terminal can also be a device such as a wearable, smart card, machine, tool, machine or container or vehicle. A terminal according to the invention is therefore either stationary or mobile.

The terminal is preferably designed to use the Internet and / or other public or private networks. For this purpose, the terminal uses a suitable connection technology, for example Bluetooth, Lora, NFC and / or WiFi and has at least one corresponding interface. The terminal can also be designed to be connected to the Internet and / or other networks by means of access to a cellular network.

In one refinement, it can be provided that the first and / or second terminal in the method shown read the received electronic coin data records when several are present or received electronic coin data sets these processes according to their monetary value. It can thus be provided that electronic coin data sets with a higher monetary value are processed before electronic coin data sets with a lower monetary value. In one embodiment, the first and / or second terminal device can be designed to connect the electronic coin data record already present in the second terminal device to the electronic coin data record already present in the second terminal device, depending on the attached information, for example a currency or denomination, and to carry out a connection step accordingly. Furthermore, the second terminal can also be designed to automatically carry out a switchover after receiving the electronic coin data set from the first terminal.

In one embodiment, additional information, in particular metadata, is transmitted from the first terminal to the second terminal during transmission, for example a currency. In one embodiment, this information can be included in the electronic coin data record.

In a preferred embodiment, the method has the following further steps: masking the transmitted electronic coin data record in the second terminal by applying the homomorphic one-way function to the transmitted electronic coin data record; and sending the masked transmitted electronic coin data set to the remote monitoring entity for the remote monitoring entity to check the validity of the transmitted electronic coin data set. In this case, for example, the entire monetary amount was transferred to the second terminal as part of the electronic coin data record. Before a payee accepts this electronic coin data record, he / she checks its validity if necessary. For this purpose, the second terminal generates the masked, transmitted electronic coin data record, sends it to the monitoring entity and in doing so asks the monitoring entity about the validity of the electronic coin data record. The monitoring instance now checks whether the masked, transmitted electronic coin data record is even present and whether it is still valid, i.e. has not already been used by another terminal, in order to avoid double spending.

In one embodiment, evidence is created in the second terminal. The evidence includes information about the correspondence of the monetary amount of the transmitted electronic coin data set with the monetary amount of the electronic coin data set to be switched. The proof preferably only includes information about the match, but not one of the monetary amounts.

The electronic coin data records of the first and / or second terminal device are preferably verified in or by the monitoring entity during the registration step. The check takes place as a function of the steps preceding the verification, for example whether a step of switching, connecting and / or dividing has taken place. The monitoring instance can for example check the validity of the (masked) transmitted and / or to be divided and / or first and second electronic coin data records. This makes it possible to determine whether the electronic coin records are being processed for the first time. If the (masked) electronic coin data sets are not valid (i.e. in particular if they are not present in the monitoring instance) the registration cannot be carried out successfully, for example because the terminal tries to issue an electronic coin data set several times.

In a further preferred refinement, the registering step, after the switching step has been carried out, comprises, for example, sending the switching command prepared by the terminal to the monitoring entity. The switchover command preferably contains the masked electronic coin data record received, the masked electronic coin data record to be switched and preferably contains further information which is needed for checks in the monitoring instance. The additional information is used to prove that the “ordering” terminal is aware of the monetary amount and the concealment amount of the electronic coin data record received without communicating the values, preferably by means of unknowledgeable evidence. zero knowledge proof. The checking entity checks the traceability of the unknowledgeable evidence, the validity of the masked electronic coin dataset received and that the monetary amount of the electronic coin dataset received is equivalent to the monetary amount of the electronic coin dataset to be switched. In order to prove that only a new concealment amount has been added to the concealment amount of the electronic coin data record received, but the monetary amount has remained the same, the second terminal device can preferably prove that the difference between the masked coin data record received and the masked coin data record to be switched has a special representation, namely that of a public key. This is done by generating a signature for the masked electronic coin data set to be switched with the added concealment amount. This generated signature of the masked electronic coin data record to be switched can then be checked in the monitoring instance, which is called Proof is that the second terminal is aware of the added obfuscation amount. Preferably, after the tests that are relevant for the switchover command have been successfully completed, that is to say with the corresponding completeness of the markings, the (masked) electronic coin data set to be switched is marked as valid. The (masked) electronic coin data set received automatically becomes invalid. The monitoring instance preferably notifies the result of executing the switchover command to the “commanding” terminal, ie which of the masked electronic coin data records involved are valid after the switchover command has been carried out.

In a further preferred embodiment, the registering step, after executing the splitting step, comprises a splitting command prepared by the terminal, which is sent to the monitoring instance, which contains the masked electronic coin data set to be split, the masked first electronic coin part data set, the masked second electronic coin part data set and preferably contains further information that is needed for checks in the monitoring instance. The additional information is used to prove that the “commanding” terminal knows the monetary amount and the concealment amount of the electronic coin data set to be divided up without communicating the values, preferably by means of unknowing evidence. zero knowledge proof. The checking instance checks the traceability of the unknowledgeable evidence, the validity of the masked electronic coin dataset to be split and that the sum of the monetary amount of the first electronic coin dataset and the monetary amount of the second electronic coin dataset is equivalent to the monetary amount of the electronic coin dataset to be split. This is preferably done in that the monitoring instance compares the sum of the masked first electronic coin part data set and the masked second electronic coin part data set with the masked coin part data set to be divided.

In a further preferred embodiment, the registering step, after the connection step has been carried out, comprises a connection command prepared by the terminal, which is sent to the monitoring entity and which contains the first masked electronic coin data record, the second masked electronic coin data record and the masked partial coin data record to be connected and preferably contains further information that is needed for checks in the monitoring instance. The additional information is used to prove that the “ordering” terminal is aware of the monetary amounts and the concealment amounts of the first and second electronic coin data records without communicating the values, preferably by means of unknowing evidence. zero knowledge proof. The verification instance checks the traceability of the unaware evidence, the validity of the masked first electronic coin data record, the validity of the masked second electronic coin data record and that the sum of the monetary amount of the first electronic coin data record and the monetary amount of the second electronic coin data record is equivalent to the monetary amount of the to connecting electronic coin data record is. This is preferably done by the monitoring entity comparing the sum of the masked first electronic coin data record and the masked second electronic coin data record with the masked partial coin data record to be connected. Preferably, after successfully completing the checks that are relevant for the connect command, that is, if the markings are complete, the (masked) electronic coin data set to be connected is marked as valid. The (masked) first electronic coin data record and the (masked) second electronic coin data record automatically become invalid. The monitoring instance preferably notifies the "commanding" terminal of the result of executing the connect command, i.e. which of the masked electronic coin data sets involved are valid after the connect command has been executed.

In one embodiment, the transmitted electronic coin data set is masked and checked before the transmitted electronic coin data set is registered in the monitoring instance.

In a preferred embodiment, the monitoring entity is a remote entity. Thus, for example, the establishment of a communication connection to the monitoring entity is provided for registering the electronic coin data record.

The monitoring instance is designed as a superordinate instance. The monitoring instance is therefore not necessarily arranged in the level or in the layer of the terminals (direct transaction layer). The monitoring entity is preferably provided for the management and checking of masked electronic coin data records and is arranged in an issuing layer, in which an issuing entity is also arranged, and / or a monitoring layer. It is conceivable that the monitoring instance also manages and checks transactions between the first and second terminals.

The monitoring instance is preferably a decentrally controlled database, English Distributed Ledger Technology, DLT, in which the masked electronic coin data sets are registered with corresponding processing of the masked electronic coin data set. In a preferred embodiment, a validity status of the (masked) electronic coin data record can be derived from this. The validity of the (masked) electronic coin data records is preferably noted in and by the checking entity. The registration of the processing or the processing steps can also relate to the registration of test results and intermediate test results relating to the validity of an electronic coin data record. If processing is final, this is indicated, for example, by corresponding markings or a derived overall marking. Final processing then decides whether an electronic coin dataset is valid or invalid.

This database is further preferably a non-public database, but can also be implemented as a public database. This database makes it possible to check coin data records for their validity in a simple manner and to prevent “double-spending”, ie multiple spending, without the payment transaction itself being registered or logged. The DLT describes a technique for networked computers that come to an agreement about the sequence of certain transactions and that these transactions update data. It corresponds to a decentralized management system or a decentralized database.

In a further embodiment, the database can also be designed as a public database.

Alternatively, the monitoring instance is a centrally managed database, for example in the form of a publicly accessible data memory or as a mixed form of a central and decentralized database.

The at least one initial electronic coin data record is preferably created exclusively by the issuer, with the divided electronic coin data records, in particular electronic coin part data records, also being able to be generated by a terminal. The creation and selection of a monetary amount preferably also includes the selection of a concealment amount with high entropy. The issuing entity is a computing system which is preferably remote from the first and / or second terminal. After the creation of the new electronic coin data record, the new electronic coin data record is masked in the issuer instance by applying the homomorphic one-way function to the new electronic coin data record in order to obtain a masked new electronic coin data record accordingly. Furthermore, additional information which is required for registering the creation of the masked new electronic coin data record in the remote monitoring entity is calculated in the issuer entity. This additional information is preferably evidence that the (masked) new electronic coin data record originates from the issuer, for example by signing the masked new electronic coin data record. In one embodiment, it can be provided that the issuer instance signs a masked electronic coin data record with its signature when generating the electronic coin data record. For this purpose, the signature of the issuing authority is stored in the monitoring authority.

Preferably, the issuing entity can deactivate an electronic coin data record that is in its possession (i.e. of which it knows the monetary amount and the concealment amount) by masking the electronic coin data record to be deactivated with the homomorphic one-way function and a deactivation command for the monitoring authority prepared. In addition to the masked electronic coin data record to be deactivated, part of the deactivation command is preferably also the proof that the deactivation step was initiated by the issuer, for example in the form of the signed, masked electronic coin data record to be deactivated. As additional information, the deactivation command could contain area checks for the masked electronic coin data record to be deactivated. The deactivation of the masked electronic coin data record is then registered in the remote monitoring entity. The deactivation step is triggered with the deactivation command.

In a further preferred embodiment, the registering step after executing the deactivation step comprises a deactivation command prepared for the issuer instance, which is sent to the monitoring instance, the masked electronic coin data record to be deactivated and preferably further information required for checks in the monitoring instance are needed, contains. The additional information serves to prove that the deactivation command was initiated by the issuer, preferably by means of the signed, masked electronic coin data record to be deactivated. The checking entity checks the signature, the validity of the masked electronic coin data set to be deactivated and optionally the area evidence of the masked electronic coin data set to be deactivated. Preferably, after the tests that are relevant for the deactivation command have been fulfilled, that is, if the markings are correspondingly complete, the (masked) electronic coin data set to be deactivated is marked as invalid. The monitoring entity preferably notifies the issuer entity of the result of executing the deactivation command, ie that the (masked) electronic coin data set to be deactivated is invalid after the deactivation command has been executed.

The creation and deactivation steps are preferably carried out in secure locations, in particular not in the terminals. In a preferred embodiment, the creation and deactivation steps are only carried out or initiated by the issuing entity. These steps preferably take place in a secure location, for example in a hardware and software architecture that was developed for processing sensitive data material in insecure networks. Deactivating the corresponding masked electronic coin data record has the effect that the corresponding masked electronic coin data record is no longer available for further processing, in particular transactions, since it has been marked as invalid in and by the monitoring entity. However, in one embodiment it can be provided that the deactivated, masked electronic coin data record remains archived at the issuer. The fact that the deactivated, masked electronic coin data record is no longer valid can be identified, for example, with the aid of a flag or some other coding, or the deactivated, masked electronic coin data record can be destroyed and / or deleted. Of course, the deactivated, masked electronic coin data record can also be physically removed from the terminal.

The method according to the invention enables various processing operations for the electronic coin data records and the corresponding masked electronic coin data records. Each of the processing operations (in particular creating, deactivating, splitting, connecting and switching) is registered in the monitoring instance and appended there in unchangeable form to the list of previous processing operations for the respective masked electronic coin data record. The processing operations "create" and "deactivate", which concern the existence of the monetary amount per se, that is, the creation and destruction or even the destruction of money, require additional approval, for example in the form of a signature, by the issuing authority to be registered (i.e. logged) in the monitoring instance. The other processing operations (splitting, connecting, switching) do not require any authorization by the issuing authority or by the command initiator (= payer, e.g. the first terminal).

Processing in the direct transaction layer only affects the ownership structure and / or the assignment of the coin data records to the terminals of the respective electronic coin data records. The respective processing in the monitoring instance is registered, for example, by means of corresponding list entries in a database which comprises a series of markings that must be carried out by the monitoring instance. A possible structure for a list entry includes, for example, column (s) for a previous coin data record, column (s) for a successor coin data record, a signature column for the issuer instance, and at least one marking column. A change in the status of the marking requires the approval of the monitoring authority and must then be saved unchangeably. A change is final if and only if the required markings have been validated by the monitoring authority, ie after the corresponding check, for example from the status "0" to the status " 1 “Were changed.

If a test fails or takes too long, it is instead changed, for example, from status “-” to status “0”. Further status values are conceivable and / or the status values mentioned here are interchangeable. Preferably, the validity of the respective (masked) electronic coin data records from the status values of the markings is summarized in a column for each masked electronic coin data record that is involved in registering the processing.

In a further exemplary embodiment, at least two, preferably three or even all of the aforementioned markings can also be replaced by a single mark, which is set when all tests have been successfully completed. Furthermore, the two columns for predecessor data sets and successor data sets can be combined into one each, in which all coin data sets are listed together. As a result, more than two electronic coin data records could be managed per field entry, and thus e.g. a split into more than two coins can be realized.

• - Sind die maskierten elektronischen Münzdatensätze der Vorgänger-Spalte(n) gültig?
• - Ergibt eine Überprüfung den korrekten Prüfwert?
• - Sind die Bereichsnachweise für die maskierten elektronischen Münzdatensätze erfolgreich?
• - Ist die Signatur des maskierten elektronischen Münzdatensatzes eine gültige Signatur der Herausgeberinstanz?

The checks by the supervisory authority to check whether processing is final are already described above and are in particular:

• - Are the masked electronic coin data records of the previous column (s) valid?
• - Does a check yield the correct test value?
• - Are the proofs of area for the masked electronic coin data records successful?
• - Is the signature of the masked electronic coin data record a valid signature of the issuing authority?

1. (1) der maskierte elektronische Münzdatensatz nicht in der Überwachungsinstanz registriert ist;
2. (2) die letzte Verarbeitung des maskierten elektronischen Münzdatensatzes angibt, dass es für ihn Vorgänger-Münzdatensätze gibt, diese letzte Verarbeitung aber nicht endgültig ist; oder
3. (3) die letzte Verarbeitung des maskierten elektronischen Münzdatensatzes angibt, dass es für ihn Nachfolger-Münzdatensätze gibt und diese letzte Verarbeitung endgültig ist.
4. (4) der maskierte elektronische Münzdatensatz nicht der Nachfolger von einem gültigen maskierten elektronischen Datensatz ist, es sei denn er ist von der Herausgeberinstanz signiert

It is also preferred that a masked electronic coin data record is invalid if one of the following checks applies, i.e. if:

1. (1) the masked electronic coin data record is not registered in the monitoring entity;
2. (2) the last processing of the masked electronic coin data record indicates that it has predecessor coin data records, but this last processing is not final; or
3. (3) the last processing of the masked electronic coin data set indicates that there are successor coin data sets for it and this last processing is final.
4. (4) the masked electronic coin record is not the successor to a valid masked electronic record unless it is signed by the issuer

In one aspect of the invention, a payment system for exchanging monetary amounts is provided with an accounting layer with a preferably decentrally controlled database, English Distributed Ledger Technology, DLT, in which masked electronic coin data records are stored; and a direct transaction layer with at least two terminals in which the method described above can be carried out; and / or an issuer entity for generating an electronic coin data record. The issuer entity can prove that the masked electronic coin data record was generated by it, the issuer entity can preferably identify itself by signing and the monitoring entity can check the signature of the issuer entity.

In a preferred embodiment, the payment system comprises an issuer instance for generating an electronic coin data record. The issuer entity can prove that the masked electronic coin data record was generated by it, the issuer entity can preferably identify itself by signing and the monitoring entity can check the signature of the issuer entity.

The payment system is preferably designed to carry out the above-mentioned method and / or at least one of the embodiment variants.

Another aspect of the invention relates to a currency system comprising an issuer entity, a monitoring entity, a first terminal and a second terminal, the issuer entity being designed to create an electronic coin data record. The masked electronic coin data record is designed to be verifiably created by the issuing entity. The monitoring entity is designed to carry out a registration step as set out in the above-mentioned method. Preferably, the terminals, i.e. at least the first and second terminals are suitable for carrying out one of the above-mentioned methods for transmitting.

In a preferred embodiment of the currency system, only the issuer is authorized to initially create an electronic coin data record. Processing, for example the step of connecting, splitting and / or switching, can and is preferably carried out by a terminal. The processing step of deactivation can preferably only be carried out by the issuing entity. Thus, only the issuing authority would be entitled to use the electronic coin data set ( C _l ) and / or the masked electronic coin data record ( Z _j , Z _k , Z _m , Z _i ) to invalidate.

The review authority ( 2 ) and the issuing authority ( 1 ) arranged in a server instance or are available as a computer program product on a server and / or a computer.

What is proposed here is a solution that issues digital money in the form of electronic coin data records that are linked to the use of conventional (analog) bank notes and / or coins is ajar. The digital money is represented by electronic coin data records. As with (analog) banknotes, these electronic coin data sets can also be used for all forms of payments, including peer-to-peer payments and / or POS payments. The knowledge of all components (in particular the monetary amount and the concealment amount) of a valid electronic coin data record is equivalent to the possession (ownership) of the digital money. It is therefore advisable to treat these valid electronic coin data records confidentially, for example to store them in a security element / safe module of a terminal and to process them there. In order to decide on the authenticity of an electronic coin data set and to prevent double spending, masked electronic coin data sets are held in the monitoring instance as a unique, corresponding public representation of the electronic coin data set. The knowledge or the possession of a masked electronic coin data record does not represent the possession of money. Rather, this is like checking the authenticity of the analog means of payment.

The monitoring instance also contains markings about executed and planned processing of the masked electronic coin data record. A status of the respective masked electronic coin data record is derived from the markings relating to the processing, which indicates whether the corresponding (unmasked) electronic coin data record is valid, i.e. is ready to pay. Therefore, a recipient of an electronic coin data set will first generate a masked electronic coin data set and have the monitoring entity authenticate the validity of the masked electronic coin data set. A great advantage of this solution according to the invention is that the digital money is distributed to terminals, dealers, banks and other users of the system, but no digital money or other metadata is stored in the monitoring instance - that is, a common instance.

The proposed solution can be integrated into existing payment systems and infrastructures. In particular, there can be a combination of analog payment processes with banknotes and coins and digital payment processes according to the present solution. A payment process can take place with banknotes and / or coins, but the change or change is available as an electronic coin data record. For example, ATMs with a corresponding configuration, in particular with a suitable communication interface, and / or mobile terminals can be provided for the transaction. An exchange of electronic coin data sets for bank notes or coins is also conceivable.
The steps of creating, switching, splitting, connecting and deactivating listed here are each triggered by a corresponding creating, switching, splitting, connecting or deactivating command.

Figure list

• 1 ein Ausführungsbeispiel eines Bezahlsystems gemäß der Erfindung;
• 2 ein Ausführungsbeispiel einer Überwachungsinstanz;
• 3 ein Ausführungsbeispiel eines Bezahlsystems gemäß der Erfindung zum Aufteilen und Umschalten von elektronischen Münzdatensätzen;
• 4 ein Ausführungsbeispiel eines Bezahlsystems gemäß der Erfindung zum Verbinden von elektronischen Münzdatensätzen;
• 5 ein Ausführungsbeispiel eines Verfahrensablaufdiagramms eines erfindungsgemäßen Verfahrens und entsprechenden Verarbeitungsschritte eines Münzdatensatzes;
• 6 ein Ausführungsbeispiel eines Verfahrensablaufdiagramms eines erfindungsgemäßen Verfahrens und entsprechenden Verarbeitungsschritte eines Münzdatensatzes;
• 7 ein weiteres Ausführungsbeispiel eines Verfahrensablaufdiagramms eines erfindungsgemäßen Verfahrens.

The invention and further embodiments and advantages of the invention are explained in more detail below with reference to figures, the figures merely describing exemplary embodiments of the invention. The same components in the figures are provided with the same reference symbols. The figures are not to be regarded as true to scale; individual elements of the figures can be shown exaggeratedly large or exaggeratedly simplified.
Show it:

• 1 an embodiment of a payment system according to the invention;
• 2 an embodiment of a monitoring entity;
• 3 an embodiment of a payment system according to the invention for dividing and switching electronic coin data sets;
• 4th an embodiment of a payment system according to the invention for connecting electronic coin data sets;
• 5 an embodiment of a method flow diagram of a method according to the invention and corresponding processing steps of a coin data set;
• 6th an embodiment of a method flow diagram of a method according to the invention and corresponding processing steps of a coin data set;
• 7th a further embodiment of a method flow diagram of a method according to the invention.

FIGURE DESCRIPTION

1 shows an embodiment of a payment system with terminals M1 and M2 according to the invention.

It is in an issuing instance 1 , for example a central bank, an electronic coin record C _i generated. To the electronic coin data record C _i we a masked electronic coin record Z _i generated, provided with a concealment amount and registered in a "concealed electronic data record ledger". In the context of this invention, a ledger is understood to be a list, a directory, preferably a database structure. The electronic coin data record C _i is sent to a first terminal M1 issued.

For example, this was used as a concealment amount r _i generates a true random number. This obfuscation amount r _i comes with a monetary amount υ _i links and then forms an i-th electronic coin data record according to the invention: $${\mathrm{C.}}_i=\left\{v_i;r_i\right\}$$

A valid electronic coin data record can be used for payment. The owner of the two values υ _i and r _i is therefore in possession of the digital money. However, the digital money is defined by a pair consisting of a valid electronic coin data record and a corresponding masked electronic coin data record Z _i . The masked electronic coin record Z _i is obtained by applying a homomorphic one-way function f ( C _i ) obtained according to equation (2): $$Z_i=f\left({\mathrm{C.}}_i\right)$$

wobei H und G Generatorpunkte einer Gruppe G, in der das diskrete Logarithmusproblem schwer ist, mit den Generatoren G und H, für die der diskrete Logarithmus der jeweils anderen Basis unbekannt ist. Beispielsweise sind G und H Generatorpunkte einer elliptischen Kurvenverschlüsselung, ECC, - also private Schlüssel der ECC, sind.Diese Generatorpunkte G und H müssen in der Art gewählt werden, dass der Zusammenhang von G und H nicht öffentlich bekannt ist, sodass bei: $$G=n\cdot H$$

die Verknüpfung n praktisch nicht auffindbar sein darf, um zu verhindern, dass der monetäre Betrag υ_i manipuliert wird und trotzdem ein gültiges Z_i berechnet werden könnte. Die Gleichung (3) ist ein „Pederson-Commitment für ECC“, das sicherstellt, dass der monetären Betrag υ_i einer Überwachungsinstanz 2 zugestanden, also „commited“, werden kann, ohne diesen der Überwachungsinstanz 2 zu offenbaren. Der öffentlichen und entfernten Überwachungsinstanz 2 wird daher nur der maskierte Münzdatensatz Z_i zugesendet (offenbart).This function f ( C _i ) is public, ie every system participant can call and use this function. This function f (Ci) is defined according to equation (3): $$Z_i=v_i\cdot H+r_i\cdot G$$

where H and G are generator points of a group G, in which the discrete logarithm problem is difficult, with the generators G and H, for which the discrete logarithm of the other base is unknown. For example, G and H are generator points of an elliptical curve encryption, ECC - i.e. private keys of the ECC. These generator points G and H must be chosen in such a way that the relationship between G and H is not publicly known, so that: $$G=n\cdot H$$

the link n must be practically impossible to find in order to prevent the monetary amount υ _i is manipulated and still a valid one Z _i could be calculated. Equation (3) is a “Pederson Commitment for ECC”, which ensures that the monetary amount υ _i a supervisory authority 2 can be granted, ie “committed”, without the monitoring authority 2 To reveal. The public and remote monitor 2 is therefore only the masked coin data record Z _i sent (disclosed).

Even if encryption based on elliptical curves is or is described in the present example, another cryptographic method would also be conceivable, which is based on a discrete logarithmic method.

Equation (3) made possible by the entropy of the amount of concealment r _i that even with a small range of values for monetary amounts υ _i a cryptographically strong one Z _i is obtained. Thus, a simple brute force attack is simply by estimating monetary amounts υ _i practically impossible.

Equation (3) is a one-way function, that is, the computation of Z _i out C _i is simple, since an efficient algorithm exists, whereas the computation of C _i starting from Z _i is very difficult, since there is no algorithm that can be solved in polynomial time.

In addition, equation (3) is homomorphic for addition and subtraction, which means that: $$Z_i+Z_j=\left(v_i\cdot H+r_i\cdot G\right)+\left(v_j\cdot H+r_j\cdot G\right)=\left(v_i+v_j\right)\cdot H+\left(r_i+r_j\right)\cdot G$$

Thus, addition operations and subtraction operations can both be carried out in the direct transaction layer 3 also in parallel in the accounting shift 4th run without the accounting shift 4th Knowledge of the electronic coin data records C _i Has. The homomorphic property of equation (3) enables the accounting of valid and invalid electronic coin data records C _i on the sole basis of the masked coin data records Z _i to lead and ensure that there is no new monetary amount υ _j was created.

wobei gilt: $$v_i=v_j+v_k$$

$$r_i=r_j+r_k$$

This homomorphic property allows the coin data set C _i according to equation (1) can be divided into: $${\mathrm{C.}}_i={\mathrm{C.}}_j+{\mathrm{C.}}_k=\left\{v_j;r_j\right\}+\left\{v_k;v_k\right\}$$

where: $$v_i=v_j+v_k$$

$$r_i=r_j+r_k$$

The following applies to the corresponding masked coin data records: $$Z_i=Z_j+Z_k$$

With equation (9), for example, a “split” processing or a “split” processing step of a coin data set according to 3 be checked without the supervisor 2 Knowledge of C _i , C _j , C _k Has. Specifically, the condition of equation (9) is checked to obtain split coin records C _j and C _k validate and validate the coin record C _i void. Such a splitting of an electronic coin record C _i is in 3 shown.

In the same way, electronic coin data records can also be combined (linked), see 4th and the explanations for it.

In addition, it is necessary to check whether (not allowed) negative monetary amounts are registered. An owner of an electronic coin record C _i must be the monitoring authority 2 can prove that all monetary amounts υ _i in a processing operation lie within a value range of [0, ..., n] without the monitoring instance 2 thereby the monetary amounts υ _i to communicate. These proofs of range are also called "range proofs". Ring signatures are preferably used as evidence of areas. For the present exemplary embodiment, both the monetary value and the concealment amount of an electronic coin data set are resolved in bit representation, ie υ _i = Σa _j * 2 ^j for 0 ^j n and a _j “element” {0; 1} and r _i = Σb _j * 2 ^j for 0≤j≤n and b _j “element” {0; 1}. A ring signature with C _ij = a _j * H + b _j * G and C _ij -a _j * H is preferably carried out for each bit, it being possible in one embodiment to carry out a ring signature only for certain bits.

In 1 becomes an electronic coin data record C _i from the issuing authority 1 and a masked electronic coin data set is generated by means of equation (3) Z _i from the issuing authority 1 calculated and this in the monitoring instance 2 registered. The first terminal then transmits M1 , which contains the electronic coin data record C _i to a second terminal M2 or can carry out one of the processing steps (switch, connect, split). The transmission takes place wirelessly via WLAN, NFC or Bluetooth, for example. The transmission can be additionally secured by cryptographic encryption methods, for example by negotiating a session key or using a PKI infrastructure.

In the second device M2 becomes the transmitted electronic coin data record C _i when C _i ^* receive. With the receipt of the electronic coin data record C _i ^* is the second terminal M2 in possession of the digital money that the electronic coin record C _i ^* represents. If both terminals trust each other, no further steps are necessary to end the process. However, the terminal is M2 not known whether the electronic coin data record C _i ^* is actually valid. In addition, the terminal could M1 the electronic coin data record C _i also transmitted to a third terminal (not shown). To prevent this, further preferred steps are provided in the method.

For checking the validity of the electronic coin data set received C _i ^* is in the second terminal M2 with the - public - one-way function from equation (3) the masked transmitted electronic coin data record Z _i ^* calculated. The masked transmitted electronic coin record Z _i ^* is then sent to the supervisory authority 2 transferred and searched there. If there is a match with a registered and valid masked electronic coin data record, the second terminal M2 the validity of the received coin data set C _i ^* displayed and it is considered that the received electronic coin data record C _i ^* equal to the registered electronic coin data record C _i is. With the check for validity, it can be determined in one embodiment that the electronic coin data set received C _i ^* is still valid, ie that it has not already been used by another processing step or in another transaction and / or has not been subject to a further change.

The electronic coin data record obtained is then preferably switched over.

It applies to the method according to the invention that the sole knowledge of a masked electronic coin data record Z _i not authorized to spend the digital money. Sole knowledge of the electronic coin dataset C _i but entitled to pay, ie to successfully carry out a transaction, especially if the coin data record C _i is valid. There is a 1-to-1 relationship between the electronic coin records C _i and the corresponding masked electronic coin records Z _i . The masked electronic coin records Z _i are in the monitoring instance 2 , for example a public decentralized database. This registration first makes it possible to check the validity of the data record, for example whether new monetary amounts have been created (illegally).

A main distinguishing feature compared to conventional solutions is that the masked electronic coin data records Z _i in a monitoring layer 4th and all processing on the electronic coin record Z _i are registered there, whereas the actual transfer of digital money is in a (secret, ie one not known to the public) direct transaction layer 3 he follows.

In order to prevent multiple spending or to ensure more flexible transmission, the electronic coin data records can now be processed in the method according to the invention. The following table 1 lists the individual operations, with the specified command also executing a corresponding processing step: Table 1 - Number of operations that are to be carried out per processing of a coin data record in the terminal or issuer instance; Further operations that are not listed here are required; Instead of the implementation mentioned, other implementations are conceivable which imply other operations Command or step Create signature Create a random number Create mask Create proof of area Produce 1 1 1 0 or 1 Deactivate 1 0 1 0 or 1 Split up 0 1 3 0 or 1 Connect 0 0 3 1 Switch 0 1 2 1

Table 1 above shows that for each coin data set, each of the processing operations “Create”, “Deactivate”, “Split”, “Connect” and “Switch” different operations “Create signature”; "Create random number";"CreateMask";"Rangechecking" can be provided, with each of the processing operations in the monitoring instance 2 registered and there in unchangeable form on a list previous processing operations for masked electronic coin records Z _i is appended. The operations of the processing “creating” and “deactivating” an electronic coin data record are only carried out in safe locations and / or only by selected entities, for example the issuer entity 1 , while the operations of all other processing on the terminals M1 to M3 can be executed.

The number of operations for the individual processing is in Table 1 with "0", " 1 "Or" 2 ". The number "0" indicates that the terminal device or the issuing instance 1 does not have to carry out this operation for this processing of the electronic coin data record. The number " 1 “Indicates that the end device or the issuing instance 1 must be able to perform this operation once for this processing of the electronic coin data record. The number "2" indicates that the end device or the issuing instance 1 must be able to perform this operation twice for this processing of the electronic coin data record.

In principle, one embodiment can also provide that an area check by the issuing authority 1 is also carried out during creation and / or deactivation.

In the following table 2, those for the monitoring instance are for the individual processing operations 2 required operations are listed: Table 2 - number of operations that are to be carried out per processing of a coin data record in the monitoring instance; Further operations that are not listed here are required; Instead of the implementation mentioned, other implementations are conceivable which imply other operations Command or step Check the signature of the publisher Check the validity of the masked electronic coin data record Understand area evidence Understand the homomorphic properties of the masked electronic coin data records, ie add them Produce 1 0 0 or 1 0 Deactivate 1 1 0 or 1 0 Split up 0 1 2 or more 1 Connect 0 2 or more 1 1 Switch 0 1 1 0

All operations in Table 2 can be performed in the monitoring instance 2 be carried out, which as a trustworthy entity, for example as a decentralized server, in particular a distributed trusted server, ensures sufficient integrity of the electronic coin data sets.

Table 3 shows the for the system participants in the payment system of 1 Preferred components to be installed: Table 3 - Preferred units in the system components Command or step Issuing authority End device Supervisor Random number generator (high security) Yes - - Random generator (deterministic) - Yes - PKI for signing Yes - - PKI for signature verification - (Yes) Yes Read access to DLT Yes Yes Yes Write access to DLT Yes Yes Yes Deactivating the electronic coin data record Yes Yes - Transport encryption Yes Yes - Secure storage (Yes) Yes -/Yes Masking unit Yes Yes - Proof of area - Yes - Check area evidence - - Yes DLT software - - Yes

Table 3 shows an overview of the preferred components to be used in each system participant, that is, the issuer instance 1 , a terminal M1 and the supervisory authority 2 . The end device M1 can be designed as a wallet for electronic coin data records, ie as an electronic purse, i.e. a data memory of the terminal in which a large number of coin data records can be stored and, for example, in the form of an application on a smartphone or IT system of a retailer, a commercial bank or of another market participant and send or receive an electronic coin data record. Thus, the components in the terminal as shown in Table 3 are implemented as software. It is assumed that the supervisor 2 based on a DLT and operated by a number of trusted market participants.

2 shows an embodiment of a monitoring instance 2 of the 1 . In the 2 an exemplary database is shown in the form of a table in which the masked electronic coin data records Z _i and, if applicable, their processing is registered. The supervisor 2 is preferably locally remote from the terminals M1 to M3 arranged and is accommodated, for example, in a server architecture.

Each processing operation for a processing (creation, deactivation, splitting, connecting and switching) is carried out in the monitoring instance 2 registered and there in unchangeable form to a list of previous processing operations for masked electronic coin data records Z _i attached. The individual operations or their test results, that is to say the intermediate results of processing, are stored in the monitoring instance 2 held.

The “Create” and “Deactivate” processes that confirm the existence of the monetary amount υ _i , in themselves, i.e. the creation and destruction of money, require additional approval from the issuing authority 1 to in the supervisor 2 to be registered (i.e. logged). The other processing operations (splitting, connecting, switching) do not require any authorization by the issuing authority 1 or by the command initiator (= payer, e.g. the first terminal M1 ).

A registration of the respective processing in the monitoring instance 2 is for example according to corresponding list entries in the database 2 realized. Each list entry has additional markings 25th to 28 that documents the intermediate results of the respective processing carried out by the monitoring instance 2 must be carried out. The markings are preferred 25th to 28 used as an aid and discarded by the checking authority after the commands have been completed. What remains are markings 29 to 32 on the validity of the (masked) electronic coin data records from the columns 22a , 22b , 23a and or 23b . When a processing command is received, these markings are, for example, in the "-" state and are changed to the " 1 "Is set and is set to" 0 "if at least one test has failed. A possible structure for a list entry of a coin data record comprises, for example, two columns 22a , 22b for a previous coin data record (O1, O2), two columns 23a , 23b for a successor coin data record ( S1 , S2 ), a signature column 24 for publisher instance (s) 1 , and four marking columns 25th to 28 . Each of the entries in the columns 25th to 28 has three alternative states "-", " 1 "Or" 0 ". The gap 25th (O flag) indicates whether a validity check for an electronic coin data record in column 23a / b was successful, with the status " 1 “Means that a validity check showed that the electronic coin record of the column 23a / b is valid and the status "0" indicates that a validity check showed that the electronic coin data record of the column 23a / b invalid and the status "-" indicates that a validity check has not yet been completed. The gap 26th (C flag) indicates whether the calculation of the masked electronic coin data set was successful, with the status " 1 “Means that a calculation was successful and the Status "0" indicates that the calculation was not successful and the status "-" indicates that a validity check has not yet been completed.

The one in column 26th The calculation to be performed is, for example: $$\left({\mathrm{<figure-callout\; id="1"\; label="Z\; O"\; filenames="DE102019002732A1\_0018.png,DE102019002732A1\_0021.png"\; state="\{\{state\}\}">Z</figure-callout>}}_O+Z_{O2}\right)-\left(Z_{\mathrm{S.}1}+Z_{\mathrm{S.}2}\right)==0$$

The gap 27 (R flag) indicates whether a check of the area records or the area records was successful, whereby the status " 1 "Means that a validity check showed that the evidence of the area or the evidence of the area is or is traceable and the status" 0 "indicates that a validity check showed that the evidence of the area or the evidence of the area could not or could not be reproduced and the state "" Indicates that a validity check has not yet been completed and was successful. The gap 28 (S flag) indicates whether a signature of the electronic coin data record matches the signature of the column 24 coincides with the state " 1 "Means that a validity check showed that the signature could be identified as that of the issuer instance and the status" 0 "indicates that a validity check showed that the signature could not be identified as that of the issuer instance and the status" - “indicates that a validity check has not yet been completed.

A change in the status of one of the markings (also known as a "flag") requires approval by the monitoring authority 2 and must then be unchangeable in the supervisory authority 2 get saved. Processing is final if and only if the required markings 25th to 28 by the supervisory authority 2 have been validated, ie after the corresponding test from the state "0" to the state " 1 "Or the state" 1 “Were changed.

In order to determine whether a masked electronic coin data set Z is valid, the monitoring entity searches 2 after the last change that affects the masked electronic coin record. It applies that the masked electronic coin data set Z is valid if and only if the masked electronic coin data set Z for its last processing in one of the successor columns 23a , 23b and this final processing is the corresponding final mark 25th to 28 having. It also applies that the masked electronic coin data set Z is valid if and only if the masked electronic coin data set Z for its last processing in one of the predecessor columns 22a , 22b is listed and this last processing has failed, i.e. at least one of the correspondingly required states of the markings 25th to 28 is set to "0".

It is also true that the masked electronic coin data set Z is not valid for all other cases, for example if the masked electronic coin data set Z is not in the monitoring instance 2 Is found; or if the last processing of the masked electronic coin data set Z in one of the successor columns 23a , 23b is listed, but this last processing never became final; or if the last processing of the masked electronic coin data set Z in one of the previous columns 22a , 22b and this last processing is final.

The audits by the supervisory authority 2 to check whether processing is final are through the columns 25th to 28 shown: the state in the column 25th indicates whether the masked electronic coin data record (s) according to previous columns 22a , 22b are valid. The state in the column 26th indicates whether the calculation of the masked electronic coin data set according to equation (10) is correct. The state in the column 27 specifies whether the area evidence for the masked electronic coin data records Z could be checked successfully. The state in column 28 indicates whether the signature in the column 24 of the masked electronic coin data record Z is a valid signature of the issuer 1 is.

The status "0" in a column 25th to 28 indicates that the test was not successful. The state " 1 “In a column 25th to 28 indicates that the test was successful. The state "-" in a column 25th to 28 indicates that no check has taken place. The states can also have a different value as long as it is possible to clearly differentiate between success / failure of a test and it is clear whether a certain test was carried out.

By way of example, five different processing operations are defined, which are explained in detail here. The corresponding list entry in 2 referenced.

One processing is, for example, “generating” an electronic coin data record C _l , Generating in the direct transaction layer 3 by the issuing authority 1 involves choosing a monetary amount υ _i and creating an amount of obfuscation r _i as already described with equation (1). As in 2 shown, there is no need for any entries / markings in the columns when processing "Create" 22a , 22b , 23b and 25th to 27 . In the successor column 23a becomes the masked electronic coin data record Z _i registered. This registration is preferably carried out before transmission to a terminal M1 to M3 , in particular or already during generation by the publisher 1 In both cases, equation (3) must be carried out. The masked electronic coin record Z _i is when creating from the publisher instance 1 signed, this signature is in the column 24 entered to ensure that the electronic coin record C _i actually by a publisher 1 was created, although other methods can also be used. Is the signature of a received Z _i with the signature in column 24 match, the marking in column 28 set (from "0" to " 1 "). The markings according to column 25th to 27 do not require a status change and can be ignored. The proof of area is not required as the monitoring instance 2 trusts the publisher 1 does not spend negative monetary amounts. In an alternative embodiment, however, it can be obtained from the publisher 1 in the create command and sent by the monitoring instance 2 being checked.

Processing is, for example, “deactivate”. The deactivation, i.e. the destruction of the money, causes the masked electronic coin data record Z _i after successful execution of the deactivate command by the publisher 1 becomes invalid. The (masked) electronic coin data record to be deactivated can therefore be found in the accounting layer 4th so do not process any more. To avoid confusion, the corresponding (unmasked) electronic coin records C _i also in the direct transaction layer 3 deactivated. When "Deactivating", the previous column becomes 22a with the electronic coin data record Z _i described, but no successor column 23a , 23b occupied. The masked electronic coin record Z _i When deactivating, check whether the signature matches the signature according to column 24 matches to ensure that the electronic coin record C _i actually by a publisher 1 but other means can be used for this test. Can that signed Z _i that is sent with the deactivate command as from the publisher instance 1 signed, the marking will be confirmed 28 set (from "0" to " 1 "). The markings according to column 26th to 27 do not require a status change and can be ignored. The markings according to column 25th and 28 are set after appropriate testing.

One processing is, for example, “splitting”. The splitting, i.e. the sharing of an electronic coin data record Z _i into two electronic coin part records Z _j and Z _k first takes place in the direct transaction layer 3 as it is in 3 is still shown with the monetary amounts υ _j and the amount of obfuscation r _j to be generated. v _k and r _k result from equations (7) and (8). In the monitoring instance 2 become the markings 25th to 27 set, the previous column 22a is with the electronic coin data record Z _i described, successor column 23a will with Z _j and successor column 23b will with Z _k described. The according to columns 25th to 27 required status changes take place after the corresponding check by the monitoring authority 2 and document the respective test result. The marking according to column 28 is ignored.

One processing is, for example, “Connect”. The connection, i.e. the merging of two electronic coin data sets Z _i and Z _j to an electronic coin data record Z _m first takes place in the direct transaction layer 3 as it is in 4th is still shown, with the monetary amount υ _m and the amount of obfuscation r _m be calculated. In the monitoring instance 2 become the markings 25th to 27 set, the previous column 22a is with the electronic coin data record Z _i described, previous column 22b will with Z _j and successor column 23b will with Z _m described. The markings in the columns 25th to 27 require status changes and the monitoring instance 2 carries out the appropriate tests. Proof of area must be provided to show that no new money has been generated. The marking according to column 28 is ignored.

gilt, so muss das zweite Endgerät M2 nachweisen können, dass sich Z_l-Z_k als skalares Vielfaches von G also als r_add*G darstellen lässt. Das heißt, dass nur ein Verschleierungsbetrag r_add erzeugt wurde und der monetäre Betrag von Z_l gleich dem monetären Betrag von Z_k ist, also Z_l =Z_k + r_add*G. Dies erfolgt durch das Erzeugen einer Signatur mit dem öffentlichen Schlüssel Z_i-Z_k=r_add*G.One processing is, for example, “toggle”. Switching is necessary when an electronic coin data record has been transferred to another terminal and a new issue by the transmitting terminal (here M1 ) should be excluded. When switching, also called "switch", the is from the first terminal M1 electronic coin record received C _k against a new electronic coin data record C _l exchanged for the same monetary amount. The new electronic coin data record C _l is from the second terminal M2 generated. This switchover is necessary in order to switch from the first terminal M1 received electronic coin data record C _k to invalidate (make invalid), which means that the same electronic coin data record is issued again C _k is avoided. Because as long as the electronic Coin record C _k is not switched, can - there the first terminal M1 with knowledge of the electronic coin data record C _k is - the first terminal M1 this electronic coin data record C _k to a third terminal M3 pass on. Switching is done, for example, by adding a new obfuscation amount r _add at the concealment amount r _k of the received electronic coin data record C _k , creating an amount of obfuscation r _i is obtained that only the second terminal M2 knows. This can also be done in the monitoring instance 2 respectively. To prove that just a new amount of obfuscation r _add at the concealment amount r _k of the masked electronic coin data record obtained Z _k was added, but the monetary amount has remained the same, and thus equation (11): $$v_k=v_l$$

applies, the second terminal must M2 can prove that Z _l -Z _k as a scalar multiple of G, i.e. as r _add * G. That is, only a concealment amount r _add was generated and the monetary amount of Z _l equal to the monetary amount of Z _k is so Z _l = Z _k + r _add * G. This is done by generating a signature with the public key Z _i -Z _k = r _add * G.

In 3 an embodiment of a payment system according to the invention for dividing and switching electronic coin data records is shown. In 3 has the first device M1 the coin data set C _i and now do not want a payment transaction with the entire monetary amount υ _i , but only with a part v _k carry out of it. The coin data record C _i divided up. To do this, the monetary amount is first divided: $$v_i=v_j+v_k$$

Each of the amounts received must be υ _j , υ _k , must be greater than 0 because negative monetary amounts are not permitted. In addition, new obfuscation amounts are derived: $$r_i=r_j+r_k$$

Then the masked coin records Z _j and Z _k according to equation (3) from the coin data sets C _j and C _k received and in the monitoring instance 2 registered. The predecessor columns are used for splitting 22a with the coin data set Z _i , the successor column 23a With Z _j and the successor column 23b With Z _k described. The markings in the columns 25th to 27 need status change and the monitoring instance 2 carries out the appropriate tests. The marking according to column 28 is ignored.

wodurch ein Verschleierungsbetrag r_l erhalten wird, die nur das zweite Endgerät M2 kennt. Um zu beweisen, dass nur ein neuer Verschleierungsbetrag r_add zum Verschleierungsbetrag r_k des erhaltenen elektronischen Münzdatensatz Z_k hinzugefügt wurde, der monetäre Betrag aber gleichgeblieben ist (υ_k = υ_l ), muss das zweite Endgerät M2 nachweisen können, dass sich Z_l-Z_k als Vielfaches von G darstellen lässt. Dies erfolgt mittels öffentlicher Signatur R_add gemäß Gleichung (15): $$\begin{array}{l}{R}_{add}=r_{add}\cdot G\\ =Z_l-Z_k=\left(v_l-v_k\right)*H+\left(r_k+r_{add}-r_k\right)*G\end{array}$$

wobei G der Generatorpunkt der ECC ist. Dann wird der umzuschaltende Münzdatensatz C_l maskiert mittels der Gleichung (3), um den maskierten Münzdatensatz Z_l zu erhalten. In der Überwachungsinstanz 2 kann dann die private Signatur r_add genutzt werden um beispielsweise den maskierten umzuschaltenden elektronischen Münzdatensatz Z_l zu signieren,, was als Beweis gilt, dass das zweite Endgerät M2 nur ein Verschleierungsbetrag r_add zum maskierten elektronischen Münzdatensatz hinzugefügt hat und keinen zusätzlichen monetären Wert, d.h. v_l = v_k .Then a coin record, here C _k from the first device M1 and the second terminal M2 transfer. In order to prevent double output, a toggle operation is useful to that of the first terminal M1 received electronic coin data record C _k against a new electronic coin data record C _l to be exchanged for the same monetary amount. The new electronic coin data record C _l is from the second terminal M2 generated. Thereby the monetary amount of the coin data record C _l adopted and not changed, see equation ( 11 ). Then, according to equation (14), a new amount of concealment is made r _add at the concealment amount r _k of the received electronic coin data record C _k added, $$r_l=r_k+r_{add}$$

whereby a concealment amount r _{l is} obtained which only the second terminal M2 knows. To prove that just a new amount of obfuscation r _add at the concealment amount r _k of the received electronic coin data record Z _k was added, but the monetary amount has remained the same ( υ _k = υ _l ), the second device must M2 can prove that Z _l -Z _k can be represented as a multiple of G. This is done using a public signature R _add according to equation (15): $$\begin{array}{l}{\mathrm{R.}}_{add}=r_{add}\cdot G\\ =Z_l-Z_k=\left(v_l-v_k\right)*H+\left(r_k+r_{add}-r_k\right)*G\end{array}$$

where G is the generator point of the ECC. Then the coin data set to be switched is C _l masked using equation (3) to obtain the masked coin data set Z _l to obtain. In the monitoring instance 2 can then the private signature r _add can be used, for example, to switch the masked electronic coin data record Z _l to sign, which is considered evidence that the second terminal M2 just an amount of obfuscation r _add added to the masked electronic coin record and has no additional monetary value, ie v _l = v _k .

The proof is as follows: $$\begin{array}{l}{Z}_k=v_k\cdot H+r_k\cdot G\\ Z_l=v_l\cdot H+r_l\cdot G=v_k\cdot H+\left(r_k+r_{add}\right)\cdot G\\ Z_l-Z_k=\left(r_k+r_{add}-r_k\right)\cdot G\\ =r_{add}\cdot G\end{array}$$

4th shows an embodiment of a payment system according to the invention for connecting electronic coin data sets. In the second terminal M2 the two coin data sets C _i and C _j receive. Based on the division according to 3 a new coin data set will now be created Z _m obtained by both the monetary amounts and the obfuscation amount of the two coin data sets C _i and C _j can be added. Then the received coin data set to be linked C _m masked and the masked coin data record Z _m is registered in the monitoring instance.

5 to 7th is in each case an exemplary embodiment of a process flow diagram of a method according to the invention 100 . Below are both 5 and 6th explained together. In the optional steps 101 and 102 a coin data record is requested and on the part of the issuing authority 1 the first device M1 provided after the electronic coin dataset has been created. A signed masked electronic coin record is created in step 103 to the supervisory authority 2 Posted. In step 103 the electronic coin data set obtained is masked C _i according to equation (3) and as in 1 explained. Then in step 104 the masked electronic coin record Z _i in the monitoring instance 2 registered. Optional can M1 toggle the received electronic coin data record. In step 105 the transfer of the coin data record C takes place in the direct transaction layer 3 to the second terminal M2 . In the optional steps 106 and 107 a validity check is carried out with prior masking, in which case the monitoring authority is successful 2 the validity of the coin data set Z _i or. C _i is confirmed.

In step 108 a received coin data set is switched over C _k (It could of course also be the received coin data set C _i can be switched) to a new coin data set C _l whereby the coin data record C _k becomes invalid and double output is prevented. This is done by the monetary amount v _k of the transferred coin data set C _k as a "new" monetary amount υ _l used. In addition, as already explained with equations (14) to (17), the concealment amount r _{l is} established. The additional amount of obfuscation r _add is used to prove that there is no new money (in the form of a higher monetary amount) from the second terminal M2 generated. Then, among other things, the masked coin data record to be switched Z _l to the supervisory authority 2 sent and switching from C _k on C _l instructed.

In step 108 ' the corresponding check is carried out in the supervisory authority 2 . It will Z _k in the column 22a according to the table in 2 entered and in column 23b the coin data set to be rewritten Z _l . A check is then carried out in the monitoring authority 2 , if Z _k is (still) valid, i.e. whether the last processing of Z _k in one of the columns 23a / b is registered (as evidence that Z _k not further split or disabled or connected) and whether a check for the last processing failed. In addition, will Z _l in the column 23b entered and the markings in the columns 25th , 26th , 27 are initially set to "0". A check is now made as to whether Z _l is valid, whereby the test according to equations (16) and (17) can be used. In the good case, the marking is in column 25th on " 1 "Is set, otherwise to" 0 ". A check is now carried out, the calculation according to equation (10) shows that Z _k and Z _l are valid and accordingly the marking in column 26th set. It is also checked whether the areas are conclusive, then the marking is in column 27 set. If all three tests were successful, and this cannot be changed in the monitoring instance 2 was held, the coin data set is considered to be switched. Ie the coin data set C _k is no longer valid and the coin data set is effective immediately C _l valid. Double output is no longer possible if a third terminal device M3 the validity of the (doubly issued) coin data set at the monitoring instance 2 he asks.

In step 109 a connection of two coin data records takes place C _k and C _i to a new coin data record C _m , whereby the coin data records C _k , C _i become invalid and double output is prevented. This is done by the monetary amount υ _m from the two monetary amounts υ _k and υ _i educated. This is done using the obfuscation amount r _m from the two obfuscation amounts r _k and r _i educated. In addition, the masked coin data set to be connected is obtained by means of equation (3) and this (together with other information) is sent to the monitoring entity 2 sent and the connection requested as processing.

In step 109 ' the corresponding check is carried out in the supervisory authority 2 . It will Z _m in the column 23b according to the table in 2 registered, which is also equal to a description. A check is then carried out in the monitoring authority 2 , if Z _k and Z _l are (still) valid, i.e. whether the last processing of Z _k or Z _i in one of the columns 23a / b is registered (as evidence that Z _k and Z _i not further split or disabled or linked) and whether a check for the last processing failed. In addition, the markings in the columns 25th , 26th , 27 initially set to "0". A check is now made as to whether Z _m is valid, whereby the test according to equations (16) and (17) can be used. In the good case, the marking is in column 25th on " 1 "Is set, otherwise to" 0 ". A check is now carried out, the calculation according to equation (10) shows that Z _i plus Z _k equal Z _m is and accordingly the marking in column 26th set. It is also checked whether the areas are conclusive, then the marking is in column 27 set.

In step 110 a coin data record is split up C _i in two coin part data sets C _k and C _j whereby the coin data record C _i is made invalid and the two divided coin part data records are to be made valid. This is done by the monetary amount υ _i in the two monetary amounts υ _k and υ _j divided up. This is done using the obfuscation amount r _i into the two obfuscation amounts r _k and r _j divided up. In addition, the masked coin part data records are obtained using equation (3) Z _k and Z _j and this with further information, for example the area tests, to the monitoring authority 2 sent and the splitting requested as processing.

In step 110 ' the corresponding check is carried out in the supervisory authority 2 . Be there Z _j and Z _k in the columns 23a / b according to the table in 2 registered. A check is then carried out in the monitoring authority 2 whether Z, is (still) valid, i.e. whether the last processing of Z _i in one of the columns 23a / b is registered (as evidence that Z _i not further split or disabled or connected) and whether a check for the last processing failed. In addition, the markings in the columns 25th , 26th , 27 initially set to "0". A check is now made as to whether Z _j and Z _k are valid, whereby the test according to equations (16) and (17) can be used. In the good case, the marking is in column 25th on " 1 " set. A check is now carried out, the calculation according to equation (10) shows that Z _i equal Z _k plus Z _j is and accordingly the marking in column 26th set. It is also checked whether the areas are conclusive, then the marking is in column 27 set.

Within the scope of the invention, all elements described and / or drawn and / or claimed can be combined with one another as desired.

List of reference symbols

1

Issuing authority

2

Supervisor

21st

Command entry

22a, b

Entry of an electronic coin data record to be modified (predecessor)

23a, b

Entry of a modified electronic coin data record (successor)

24

Signature entry

25th

Marking the validity check

26th

Marking the calculation test

27

Marking the area verification check

28

Marking the signature verification

3

Direct transaction layer

4th

Accounting shift

M1

first terminal

M2

second terminal

M3

third terminal

C _i

electronic coin data record, net note

C _j , C _k

split electronic coin part data record, split net note

C _l

electronic coin data record to be switched

C _m

Electronic coin data record to be linked

Z _i

masked electronic coin record, mask note

Z _j , Z _k

masked split electronic coin part record, split mask note

Z _l

masked electronic coin data record to be switched

Z _m

masked electronic coin data record to be connected

υ _i

Monetary amount

υ _j , υ _j

Split monetary amount

υ _l ,

Monetary amount of a switchable / switched electr. Coin data set

υ _m ,

Monetary amount of an electr. Coin record

r _i

Obfuscation amount, random number

r _j , r _j

Obfuscation amount of a split electronic coin record

r _m

Obfuscation amount of an electronic coin data record to be linked / linked

C _i ^*

transmitted electronic coin data record, net note

C _j ^* , C _k ^*

transmitted split electronic coin part data set, split net note

Z _i ^*

masked transmitted electronic coin data record

Z _j ^* , Z _k ^*

masked transmitted split electronic coin record

f (C)

Homomorphic one-way function

[Z _i ] Sig _l

Signature of the publisher authority

101-108

Method steps according to an embodiment

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102009038645 A1 [0005]
• DE 102009034436 A1 [0005]
• WO 2016/200885 A1 [0006]

Claims (18)

A method (100) for the direct transmission of electronic coin data sets (C _i , C _j , C _k , C _m , C _l ) between terminals (M1, M2, M3), wherein a first terminal (M1) has at least one electronic coin data set (C _i , C _j , C _k , C _m , C _l ), with the steps: - Transferring (105) the electronic coin data set (C _i , C _j , C _k ) from the first terminal (M1) to a second terminal (M2 , M3), the at least one electronic coin data set (C _l C _j , C _k ) having a monetary amount (υ _j , υ _j , υ _k ) and a concealment amount (r _l , r _j , r _k ). - Receiving the electronic coin data set (C _l C _j , C _k , C _m ) from the first terminal (M1) as a transmitted electronic coin data set (C _i ^* , C _j ^* , C _k ^* , C _l ^* , C _m ^* ) in second terminal (M2, M3); and - switching the transmitted electronic coin data set (C _i ^* , C _j ^* , C _k ^* ) with the steps: ◯ Generating an electronic coin data set (C ₁ ) to be switched in the second terminal (M2, M3) from the transmitted coin data set (C _i ^*) , C _i ^* , C _k ^* ), where ◯ is a concealment amount (r _l ) for the electronic coin data set to be switched (C _i ) using a transmitted concealment amount (r _k ^* ) of the transmitted electronic coin data set (C _k ^* ) in the second terminal ( M2, M3) is generated; and ◯ the transmitted monetary amount (υ _k *) of the transmitted electronic coin data set (C _k ^* ) is used as a monetary amount (υ _l ) for the electronic coin data set (C _l ) to be switched over; and / or - splitting the transmitted electronic coin data set (C _i ^* ) into a first electronic coin part data set (C _j ) and a second electronic coin part data set (C _k ) in the second terminal (M2, M3), the transferred monetary amount (υ _i ^* ) is divided into the at least first and second monetary amounts (υ _j , υ _k ); and / or - connecting a first and a second electronic coin data set (C _l ^* ; C _j ^* ) to a connected electronic coin data set (C _m ) in the second terminal (M2, M3) with the steps: o Calculating a concealment amount (r _m ) for the electronic coin data set (C _m ) to be connected by forming the sum of the respective concealment amounts of the first and second electronic coin data sets (r _i ^* , r _j ^* ); and o calculating the monetary amount (υ _m ) for the electronic coin data set (C _m ) to be connected by forming the sum from the respective monetary amounts (υ _l ^* , υ _j ^* ) of the first and second electronic coin data sets (C _l ^* ; C _j ^* ); - The following steps are also carried out: - Masking (103) an electronic coin data set (C _j , C _k , C _m , C _l ), in particular the coin data set to be switched, the first and / or second coin part data set and / or associated coin data set, im second terminal (M2, M3) by applying a homomorphic one-way function (f (C)) to the electronic coin data set (C _j , C _k , C _m , C _l ) to obtain a masked electronic coin data set (Z _j , Z _k , Z _m , Z _l ); and - registering (104) the masked electronic coin data set (Z _j , Z _k , Z _m , Z _l ) in a monitoring entity (2). The method (100) according to Claim 1 with the further process steps: Masking (106) the transmitted electronic coin data set (C _j ^* , C _j ^* , C _k ^* , C _l ^* , C _m ^* ) in the second terminal (M2) by applying the homomorphic one-way function (f (C )) on the transmitted electronic coin data set (C _l ^* , C _j ^* , C _k ^* , C _l ^* , C _m ^* ) to obtain a masked transmitted electronic coin data set (Z _i ^* , Z _j ^* , Z _k ^* , Z _l ^* , Z _m ^* ); and - sending the masked transmitted electronic coin data set (Z _l ^* , Z _j ^* , Z _k ^* , Z _l ^* , Z _m ^* ) to the monitoring entity (2) for checking (107) the validity of the transmitted electronic coin data set (C _j ^*) , C _j ^* , C _k ^* , C _l ^* , C _m ^* ) by the monitoring entity (2). The method according to one of the Claims 1 or 2 , wherein after the step of switching the registering step comprises: - receiving the masked electronic coin data set (Z _l ) to be switched in the monitoring instance (2); Checking the masked electronic coin data set to be switched over for validity; - Registering the masked electronic coin data set (Z _l ) to be switched over in the monitoring instance (2), whereby the electronic coin data record (Z _l ) to be switched over is considered valid (108). The method (100) according to one of the preceding claims, further comprising a step of creating a proof in the second terminal (M2, M3), wherein the proof comprises information that the monetary amount (v _i ^* , v _j ^* , v _k ^* ) of the transmitted electronic coin data set (C _j ^* , C _j ^* , C _k ^* , C _l ^* , C _m ^* ) is equal to the monetary amount (v _l ) to be switched over to electronic coin data set. The method (100) according to one of the preceding claims, wherein the step of registering includes checking at least one of the electronic coin data sets (Z _l, Z _j , Z _k , Z _m , Z _l ) in the monitoring instance (2) as a function of the preceding steps is carried out. The method (100) according to any one of the preceding claims, wherein the at least one electronic coin data set (C _j ) was generated by an issuing entity (1). The method (100) according to Claim 6 , the issuer entity (1) signing a masked electronic coin data record (Z _l ) with its signature ([Z _i ] Sig _l ) and this signature ([Z _i ] Sig _I ) being stored in the monitoring entity (2). The method (100) according to one of the preceding claims, wherein an electronic coin data record (C _j ) is created by marking the corresponding masked electronic coin data record (Z _i ) in the monitoring entity (2) and / or by deactivating the corresponding masked electronic coin data record (Z _l ) becomes invalid in a publisher instance (2). The method (100) according to one of the preceding claims, wherein the monitoring instance (2) is a decentrally controlled database, English Distributed Ledger Technology, DLT, in which the masked electronic coin data sets (Z _l Z _j , Z _k , Z _m , Z _l ) are registered with corresponding processing of the masked electronic coin data set (Z _i , Z _j , Z _k , Z _m , Z _l ). A payment system for exchanging monetary amounts, the payment system comprising: a monitoring layer (4) with a preferably decentrally controlled database, English Distributed Ledger Technology, DLT, in which masked electronic coin data records are stored; and - a direct transaction layer (3) with at least two terminals (M1, M2, M3), in which the method (100) according to one of the preceding Claims 1 to 9 is feasible; and / or an issuer instance (1) for generating an electronic coin data set (C _l ) and preferably a signature ([Z _i ] Sig _I ), the signature ([Z _i ] Sig _I ) being stored in the database. Currency system, comprising an issuer entity (1), a monitoring entity (2), a first terminal (M1) and a second terminal (M2, M3), the issuer entity being designed to create an electronic coin data record (C _l ), the masked electronic coin data set (Z _i ) is designed to be verifiably created by the issuing entity (1), the monitoring entity (2) for performing a registration step according to one of the Claims 1 to 9 is trained. Monetary system according to Claim 11 , whereby only the issuing authority (1) is authorized to create the electronic coin data set (C _j ). Monetary system according to Claim 11 or 12 , the issuer entity (1) signing the electronic coin data set (C _l ) with its signature ([Z _i ] Sig _I ) and this signature ([Z _i ] Sig _I ) being stored in the monitoring entity (2). Monetary system according to one of the Claims 11 to 13 , wherein the first and second terminals (M1, M2, M3) for performing a method according to one of the Claims 1 to 9 are trained. Monetary system according to one of the Claims 11 to 14th , the checking of the masked electronic coin data set (Z _j , Z _k , Z _m , Z _l ) by the checking entity (2) as valid if the masked electronic coin data set (Z _j , Z _k , Z _m , Z _l ) from the issuing authority (1) comes from. Monetary system according to one of the Claims 11 to 15th , whereby only the issuing authority (1) is authorized to invalidate the electronic coin data record (C _i ) and / or the masked electronic coin data record (Z _j , Z _k , Z _m , Z _l ). Monetary system according to one of the Claims 11 to 16 , the checking entity (2) and the issuing entity (1) being implemented as a server entity, in particular as a computer program product on a server and / or a computer. Monetary system according to one of the Claims 11 to 17th , wherein the first and / or second terminal (M1, M2, M3) as a mobile terminal, in particular as a smartphone, a tablet computer, a computer Server or a machine, and / or as a passive terminal device, in particular a smart card or a wearable.

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